The hand-held transmitters or control units and the remote receivers and servos used with them in the control of slave devices such as powered model airplanes, boats, cars and the like all utilize batteries, or battery packs, usually of the nickel-cadmium cell type. It is a characteristic of these batteries that on a momentary voltage check, without a short, preceding power drain, they exhibit a satisfactory voltage level. However, on a subsequent power drain of even short duration the voltage level may fall substantially.
The battery checking device of the present invention measures both the voltage and current, the energy level, of the battery and is thus particularly adapted for checking nickel-cadmium battery cells. The circuit is relatively simple in configuration and utilizes diodes and an SCR switching element and thus has no moving parts. No external batteries or power source for the checker is required and a means is provided for adjustably adapting the checker for various battery voltages within a predetermined range. The device is small, pocket size, and plugs directly into the battery to be checked without requiring that the battery be removed from the model.